This invention relates generally to laser scanning apparatus and more particularly to fix-mounted, e.g., counter type, laser scanning apparatus.
Various laser-based scanning systems have been disclosed in the patent literature and many are commercially available to read bar codes, e.g., the uniform product code, which is imprinted on packaging for product, or on the product itself, or on some other item.
One type of scanning system is referred to as a counter or "slot scanner". Such devices are generally mounted within a housing in a checkout counter of a supermarket or other retail establishment, and include a window at the top thereof through which a scanning pattern is projected. The scanning pattern is created by a laser and associated optical components, e.g., mirrors, etc., which typically produce plural scan lines which are either parallel to one another and/or intersect one another. When an item bearing a bar code is brought into the field of the scan pattern so that the pattern traverses the bar code light is reflected off of the bar code and is received back through the window of the slot scanner, whereupon decoding means converts the received light into an electrical signal indicative of the bar code. These signals can then be utilized to identify the article bearing the code and provide pricing information.
In order to ensure that a bar code is traversed suffiiently so that it can be read accurately irrespective of its orientation within the scan pattern, prior art counter scanners have utilized various optical configurations including mirrors, prisms, and the like to fold the laser beam and create complex patterns. Examples of such patterns are comb patterns, orthogonal patterns, interlaced patterns, star-like patterns, etc. While such patterns may be suitable for their purposes, the means for creating them has resulted in housings which were quite large in size.
In my U.S. Pat. No. 4,713,532 there is disclosed a counter or slot scanner producing an aggressive scanning pattern having three rastered groups of intersecting scan lines to form a large "sweet spot" to enable the bar code to be read omnidirectionally, i.e., irrespective of its orientation with respect to the scanner. That scanner is housed within a very compact, small footprint housing which is arranged to be mounted under a counter or disposed on a counter. Depending upon the orientation of the scanner, its window may be horizontal or at some other orientation, e.g., vertical. Devices embodying the teachings of that patent have been sold by the assignee of that patent (and of this application), Metrologic Instruments, Inc., under the designation MS260.
Metrologic Instruments, Inc. has also sold other compact counter or slot scanners under the designation MS360. Those scanners also produce a broad, aggressive scan pattern. In that case the pattern is made up of five rastered groups of intersecting scan lines.
While the aforementioned counter scanners have proved suitable for their intended purposes it has been determined that in certain applications the production of a broad scanning pattern is less than optimum. For example, in some check-out counter applications it is desirable to create a scanning pattern which, although aggressive, is confined within a relatively narrow volume, to prevent unintentional scanning of nearby objects. Hand-held scanners while providing for scanning within a confined volume (to prevent unintentional scanning), nevertheless suffer from various drawbacks, one of which being aggressiveness of the scanning pattern.
Thus, the need exists for a scanner device which combines the versatility of a hand-held scanner with the aggressiveness of a counter or slot scanner.
In many mass merchandizing applications it is desirable to have a scanner with the aggressiveness of a counter or slot scanner but which does require that the scanner be mounted or disposed with its window on the counter where it may present a snagging hazard to bar coded items, e.g., garments on hangers or hooks, if they are dragged across the counter for scanning. In other applications, e.g., where bar coded items are packaged in such a way as to require that they not be inverted, it is also desirable to provide an aggressive, fixed mount scanner to project the scanning pattern down toward the counter from above so that items can be scanned right-side-up.
Thus, the need also exists for a counter mounted scanner which can project an aggressive scanning pattern from the side or above to scan items brought into the pattern, yet which pattern is relatively confined to minimize counter space required to be clear of bar coded items.
Some commercially available scanners are arranged to be disposed or mounted to project a scanning pattern somewhat laterally to act as a "projection scanner". Examples of such scanners are the following: the "FREEDOM" scanner sold by Spectra Physics, the "7852" scanner sold by NCR, the "OMNISCAN" scanner sold by Microvideo, and the "SLIMSCAN" scanner sold by Fujitsu. While such scanners are generally suitable for their intended purposes they all suffer from one or more drawbacks, such as somewhat large housing and/or "footprint" size, amount of counter space to be kept clear of bar coded items, somewhat restricted working range, inability to scan all types of bar codes omnidirectionally and lack of agressiveness of scan pattern.